A Review of the Effect of Trace Metals on Freshwater Cyanobacterial Growth and Toxin Production

Abstract

Cyanobacterial blooms are becoming more common in freshwater systems, causing ecological degradation and human health risks through exposure to cyanotoxins. The role of phosphorus and nitrogen in cyanobacterial bloom formation is well documented and these are regularly the focus of management plans. There is also strong evidence that trace metals are required for a wide range of cellular processes, however their importance as a limiting factor of cyanobacterial growth in ecological systems is unclear. Furthermore, some studies have suggested a direct link between cyanotoxin production and some trace metals. This review synthesises current knowledge on the following: (1) the biochemical role of trace metals (particularly iron, cobalt, copper, manganese, molybdenum and zinc), (2) the growth limitation of cyanobacteria by trace metals, (3) the trace metal regulation of the phytoplankton community structure and (4) the role of trace metals in cyanotoxin production. Iron dominated the literature and regularly influenced bloom formation, with 15 of 18 studies indicating limitation or colimitation of cyanobacterial growth. A range of other trace metals were found to have a demonstrated capacity to limit cyanobacterial growth, and these metals require further study. The effect of trace metals on cyanotoxin production is equivocal and highly variable. Better understanding the role of trace metals in cyanobacterial growth and bloom formation is an essential component of freshwater management and a direction for future research.

Influence of Abiotic Factors on the Growth of Cyanobacteria Isolated from Nakdong River, South Korea1

“…Nitrate and phosphate are essential macronutrients and are dominant sources of nitrogen and phosphorous for phytoplankton, respectively (Dortch 1990, Facey et al. 2019). Nitrate‐nitrogen (NO 3 ‐N) concentration had a direct relationship with growth.…”

“…2017, Facey et al. 2019). It has been stated that nitrogen and phosphorus inputs in water bodies promote cyanobacterial growth (Cai and Kong 2013, Bui et al.…”

Nitrogen and metal pollution in the southern Caspian Sea: a multiple approach to bioassessment

“…The analysis of metals in sediment and macroalgae were performed by the Institute for Nano Science and Nanotechnology at Sharif University of Technology (Iran). In this research, we considered metals with well-known anthropic origins and metals that are naturally found in the Iranian Caspian Sea sediments (for further details, see Agah et al 2011 ) and can limit the algal growth and blooms (e.g., Fe; Bruland et al 2001 ; Facey et al 2019 ; Sunda 2006 ). High concentrations of these metals in sediments and macroalgae can indicate metal pollution due to anthropic activities (Caccia et al 2003 ; Caliceti et al 2002 ; Chakraborty et al 2014 ; Ghosh et al 2019 ), and by biomagnification, they can become potentially toxic (Adel et al 2017 ; Dadar et al 2016 ).…”

Co-Occurrence of Cyanobacteria and Cyanotoxins with Other Environmental Health Hazards: Impacts and Implications

“…Further investigations into microcystin production by M. aeruginosa , Microcystis novacekii , and Phormidium autumnale cultures have included increases upon iron addition but also increases upon iron limitation during culture. Positive effects of copper, zinc, and manganese ions on microcystin production under conditions of metal enrichment of, and metal limitation of, cyanobacterial cultures have also been observed, possibly indicating physiological and biochemical roles of the metals in microcystin biosynthesis, in addition to a siderophore function for microcystins in metal acquisition [ 98 ]. No specific differences in anatoxin-a production by P. autumnale were found in response to growth under an environmentally encountered, low-to-high range of iron or copper concentrations [ 99 ].…”